When stitching patterns stored in the electronic sewing machine on a fabric, an end part of the fabric to be stiched is stepped with several stitchings of finish-up to avoid ravellings of the stitch. The sewing machine is stopped automatically after the finish-up stitchings, irrespective of an amount of operation a machine controller.
There are in general two ways of stopping the sewing machine i.e., a forcible braking by using the braking of electricity, and a natural stopping by only stopping the supply of electricity. We would refer to the latter in view of cost merits.
A position to be stopped is determined with reference to a certain range about an upper dead point of a needle bar, and the finish-up stitching is carried out at low speed, so that the needle bar stops within said range. On the other hand, ordinary patterns are formed by controlling the amount of operation of the controller at optional speed from a low speed to a high speed.
No problem occurs, when the pattern is stitched at the low speed and the finish-up stitching is selected. If the finish-up stitching is selected while the ordinary pattern is being stitched at the high speed, it takes a long time for the rotation speed of the sewing machine to change from the high speed to the low speed. If an inertia of a load of the machine motor is large, the time of changing from the high speed to the low speed is also large. Then, although the finish-up stitching is ended at the determined several steppings, the speed does not become fully low. If trying to stop the needle bar under such a condition, the needle bar stops outside of the range, and as the case may be, the needle bar goes down nearly to the lower dead point and stops as it still penetrates a fabric. This is inconvenient to a machine operator, and the function of the sewing machine is often adversely affected.
As far as the finish-up stitching plays a role of avoiding the ravellings, the lesser stitchings are desirable. However, due to inconveniences as said above, the finish-up stitches are formed with excess stitchings. This is wasteful, and the operator feels nervous about spending much time on this operation.